%0 Journal Article %A Cunkle, C.H. %T A note on Boolean operations %J Portugaliae mathematica %D 1959 %P 177-179 %V 18 %N 3 %I mathdoc %U http://geodesic.mathdoc.fr/item/PORMA_1959__18_3_114822/ %G en %F PORMA_1959__18_3_114822